I rent the basement apartment that accounts for 1/3 of my house. My family occupies the other 2/3rds. In 2016, the basement unit was rented for 121 days. Do I claim 1/3 of the mortgage interest I paid for 121 days (or does Turbotax calculate the amount o

Wouldn't it be simpler to just claim all the mortgage interest I paid as a regular deduction and not claim mortgage interest at all under the rental property (because we would have paid the interest regardless of whether we had the unit rented).